bump up version for external dependency on clutter

[Emmanuele Bassi <ebassi gmail com>]

hi everyone;

yesterday I did a release of the stable branch of Clutter and
Clutter-GTK. there are a lot of bug fixes, including a crasher that
affected gnome-games, so I'd like to request a bump for the minimum
required version of Clutter 0.8 from 0.8.2 to 0.8.8 and for Clutter-GTK
from 0.8.2 to 0.8.3.

ciao,
 Emmanuele.

-- 
Emmanuele Bassi,
W: http://www.emmanuelebassi.net
B: http://log.emmanuelebassi.net